<!-- css -->
<style>
    body {
        margin: 0;
        padding: 0;
    }

    .main {
        display: flex;
        justify-content: center;
        align-items: center;
        height: 600px;
        width: 600px;
        background-color: pink;
    }

    .item {
        height: 100px;
        width: 100px;
        background-color: #ff5;
    }
    .container {
    width: 8px;
     height: 16px;
     border-color: rgba(117,200,43,1);
     border-style: solid;
     border-width: 0 2px 2px 0;
     transform: rotate(45deg);
   }

</style>
<!-- html -->

<body>
    <div class="container">
        <div class="item">
        </div>
    </div>
</body>